Route method for embossment numerical control machining
By using a marking-machining-point algorithm to adjust the tool path in CNC relief carving, the problem of severe tool wear in hard materials was solved, resulting in extended tool life and improved machining efficiency.
Patent Information
- Application Number
- CN202510984646.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-17
- Publication Date
- 2025-10-28
AI Technical Summary
In current CNC relief carving, the cutting tools used for hard materials such as stone and hardwood suffer severe wear, resulting in short tool life and affecting processing efficiency and cost.
A path method for relief CNC machining is adopted. A 3D model is generated by CAM programming software, the model is edited and modified, the tool and machining strategy are selected, the machining point marking algorithm is used to compare the machining point depth, a new machining path is generated, and the tool path is adjusted to reduce tool bottom wear.
It reduces tool wear, extends tool life, saves resources and energy, improves processing efficiency and material yield, protects machine tool components, and reduces the labor intensity of operators.
Smart Images
Figure CN120848366A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of CNC relief carving technology, specifically to a path method for CNC relief carving. Background Technology
[0002] Relief carving is a type of curved surface processing. Relief carving is a common form of sculpture, widely used in architectural decoration, furniture manufacturing, handicrafts, mold making, and other fields. It highlights the subject matter by removing excess material, presenting a three-dimensional aesthetic. Figures 1-2 As shown.
[0003] With social development and technological progress, more and more reliefs are being processed using CNC engraving machines, such as stone reliefs, wood reliefs, and metal reliefs.
[0004] For relief carving on soft materials like wood, the material's low hardness results in minimal tool wear during the carving process. Conversely, for relief carving on hard materials like stone, the high hardness of the material, especially granite (typically with a Mohs hardness of 6 to 7), leads to significant tool wear during CNC machining.
[0005] CNC relief carving processing paths are divided into roughing paths and finishing paths.
[0006] In CNC relief carving, where products have high value, high precision requirements, and limited tooling capabilities, such as relief carving of steel molds, roughing is typically performed first, followed by finishing. The roughing path uses a larger tool to remove material in layers, reducing the cutting amount of the subsequent finishing tool and extending its lifespan.
[0007] In CNC relief carving, where product value is low, precision requirements are low, and tooling capabilities are high, such as stone and wood relief carving, users typically skip roughing and go directly to finishing to improve efficiency. However, the finishing paths provided by CNC programming software on the market can lead to significant tool wear on hard materials like stone. The higher the material's hardness, the more severe the tool wear. For example, in CNC relief carving of hard woods like mahogany, tool wear on the bottom is greater than in woods of average hardness like pine and cypress; similarly, in CNC relief carving of hard granite, tool wear on the bottom is greater than in stones of average hardness like sandstone, white marble, and bluestone.
[0008] like Figure 3As shown, the commonly used cutting tool in CNC machining of stone relief is the tapered ball end mill. During CNC relief machining, the rotational speed at the center point of the tool's bottom is 0. The closer to the center point, the lower the rotational speed and the worse the machining capability. The machining capability at the bottom of the tool is far less than that at the side edges, with the center point being the weakest. Most tool failures in CNC machining of stone relief are caused by damage to the tool's bottom. When the tool's bottom wears to a certain extent, its machining capability is insufficient for normal cutting. Even if the wear on the side edges is less, the entire tool must be replaced promptly; otherwise, it may lead to breakage of the tool's bottom or even the entire tool.
[0009] The global CNC engraving machine market continues to grow, and stone engraving machines, as an important component of this market, are also expanding with technological advancements and the broadening of their application areas. Therefore, there is a need to design a path method for relief CNC machining to address the problems of high tool wear and short tool life in the current machining of relief workpieces made of different materials. Summary of the Invention
[0010] In view of the problems existing in the prior art, the purpose of this invention is to provide a path method for CNC machining of relief.
[0011] The technical solution adopted by this invention to solve its technical problem is: a path method for CNC machining of relief carving, comprising the following steps:
[0012] S1. Generate a 3D relief model: CAM programming software generates a 3D relief model;
[0013] S2. Modify the 3D relief model: Edit and modify the shape of the 3D relief model;
[0014] S3. Select the tool and machining strategy, and input various machining parameters, including but not limited to tool type, machining strategy, and machining path parameters;
[0015] S4. Calculate and generate machining path: Using an algorithm to mark machining points, find machining points that are prone to wear in the finishing path. By comparing the depth of the machining points and the comparison points, the depth difference between the machining points and the comparison points is obtained. The depth difference is compared with the value input by the user to obtain the marked machining points. The machining path of the tool is determined by marking the machining points. The machining path is automatically calculated, analyzed and modified to generate a new machining path.
[0016] S5. Output processing file: Generate a processing file from the new processing path in step S4; or the user can skip steps S1-S3 and directly input an existing relief processing file to generate a processing path, and then perform the operation in step S4 to recalculate, analyze and modify the processing path to obtain a new processing file.
[0017] S6. CNC engraving machine processing: The final processing file is loaded into the control system of the CNC engraving machine for processing.
[0018] Specifically, in step S1, a three-dimensional relief model is generated within the CAM programming software. The three-dimensional relief model file includes, but is not limited to, inputting a three-dimensional model in STL format, inputting a grayscale image into the CAM programming software and generating a three-dimensional relief model based on the grayscale image, and opening a file containing the three-dimensional model.
[0019] Specifically, the size modification of the three-dimensional relief model in step S2 includes the width (X-axis horizontal dimension), the length (Y-axis vertical dimension), and the depth (Z-axis vertical dimension).
[0020] Specifically, the types of tools used in step S3 include, but are not limited to, ball end mills, tapered ball end mills, and tapered flat end mills;
[0021] The machining strategy adopts a surface machining strategy, which is a surface finishing strategy;
[0022] The machining path parameter settings include the tool path mode, which includes, but is not limited to, parallel section finishing, circumferential equidistant finishing, and spiral equidistant finishing.
[0023] Specifically, the algorithm for marking machining points in step S4 is to calculate the depth of the tool's bottom center point into the material. In all tool path types, the distance between each pair of adjacent paths is very small. The machining depth of the current path is directly related to the machining depth of the previous path that has been completed. There is a machining point B in the current path. In the XY view of the path, a perpendicular line is drawn from point B to the previous path, with the foot of the perpendicular being point A. Point A is located on the previous path, that is, point A is the machining point of the previous path that is closest to point B in the XY view. The planar distance between point A and point B in the XY view is a "path spacing". At this time, point A is called the "comparison point" of point B, and the Z-axis distance between point A and point B is called the "Z-axis comparison distance".
[0024] "Z-axis comparison distance" is the depth of the cutting tool bottom center point into the material in the Z-axis direction at the current machining point;
[0025] The "Z-axis comparison distance marker value" is set to d (user input parameter), and the "Z-axis comparison distance" is set to h. A depth comparison is performed between the machining point and the comparison point, resulting in the following three outcomes:
[0026] (1) When h≤0, the center point of the bottom of the tool does not cut into the material, which is called the "non-cutting point" and is not marked.
[0027] (2) When 0 < h ≤ d, the center point of the tool bottom cuts into the material, but the machining depth is small. This is called the "slight cutting point" and is not marked.
[0028] (3) When h > d, the center point of the bottom of the tool cuts into the material and the machining depth is large. This is called a "severe cutting point". It is marked and this type of machining point is called a "marked point". The unmarked point is called an "unmarked point".
[0029] Specifically, the marked processing points form marked path segments. The relief processing path is composed of numerous processing points connected by line segments to fit the curved surface. A local path composed of several adjacent processing points is called a "path segment". The relief processing path is composed of path segments, and path segments are composed of processing points. A small path segment composed of two adjacent processing points is called a "path sub-segment". All processing points on the relief processing path are divided into two types: "unmarked points" and "marked points". "Unmarked points" form "unmarked path segments", and "marked points" form "marked path segments". Two adjacent "marked points" form a "marked path sub-segment", and several adjacent "marked path sub-segments" form a "marked path segment". That is, all processing points in a "marked path segment" are "marked points". The marked path segment is composed of "marked points" and has a processing direction. If the processing points adjacent to both sides of a "marked point" are "unmarked points", then this point is called a "marked isolated point" and is not processed.
[0030] Specifically, the angle between the marked path segment and the horizontal line is compared with the angle value input by the user and classified into marked horizontal path segments, marked uphill path segments, and marked downhill path segments. The angle value input by the user is called the uphill / downhill angle. The angle between the marked path segment and the horizontal line is calculated. Path segments with angles smaller than the uphill / downhill angles are called marked horizontal sub-segments; path segments with angles greater than or equal to the uphill / downhill angles and with the processing direction upward are called marked uphill sub-segments; path segments with angles greater than or equal to the uphill / downhill angles and with the processing direction downward are called marked downhill sub-segments; path segments composed of marked horizontal sub-segments are called marked horizontal path segments; path segments composed of marked uphill sub-segments are called marked uphill path segments; and path segments composed of marked downhill sub-segments are called marked downhill path segments.
[0031] Specifically, the bottom of the marked path segment in a "V" shape is flattened, and the user inputs a value for "flattening width" as a reference parameter to control the "bottom horizontal width" after flattening.
[0032] Specifically, the method for changing the tool path of the marked path segment includes Z-axis layered multiple machining, marked downhill path segment reverse tool path, and step-type reciprocating side milling. The Z-axis layered multiple machining steps include: (1) horizontal layered multiple machining, (2) Z-axis distance equally divided layered multiple machining, and (3) combined layered multiple machining.
[0033] Mark the downhill path segment and reverse the tool path to change the original machining direction from high point to low point to low point to high point. Reverse the direction and change the cutting position of the bottom of the tool.
[0034] Step-type reciprocating side milling adopts a one-forward-one-backward method, which indirectly reduces the processing speed and facilitates tool cooling and removal of processing residue when retracting the tool. Step-type reciprocating side milling is divided into three cases and uses corresponding algorithms: (1) Equal height path segment: all processing points on the path segment have the same Z-axis height, (2) Ascending path segment: the Z-axis height of the next processing point is always higher than the previous processing point, (3) Descending path segment: the Z-axis height of the next processing point is always lower than the previous processing point.
[0035] Specifically, the strategy for changing the tool path by marking the path segment is as follows: the marked path segment is divided into a single marked path segment and a compound marked path segment; if the marked path segment contains only one of the marked horizontal path segment, marked uphill path segment, and marked downhill path segment, then the marked path segment is called a single marked path segment; if the marked path segment contains two or more of the marked horizontal path segment, marked uphill path segment, and marked downhill path segment, then the marked path segment is called a compound marked path segment.
[0036] The machining of the path segment that exceeds the segment is performed using step-by-step reciprocating side milling.
[0037] The present invention has the following beneficial effects:
[0038] The relief CNC machining path method designed in this invention can reduce the wear of the tool bottom during machining. Specifically, it uses an intelligent algorithm to compare the machining points of traditional finishing paths, find the path segments that are prone to causing wear on the tool bottom, and obtain a new machining path and generate a machining file by adjusting the machining speed and changing the tool path of the path segments. Finally, the CNC engraving machine executes the new machining file to engrave and obtain the relief product.
[0039] This invention actively responds to the national call for conserving resources and energy, improving production efficiency, and ensuring safe production. It reduces tool wear during CNC machining of stone reliefs through intelligent algorithms. Reducing tool wear is of great significance, mainly in the following aspects:
[0040] 1) Save tool resources: Extend tool life and reduce tool waste, thereby reducing the waste of resources such as steel, alloys, diamond particles, and tool binders.
[0041] 2) Improve the yield rate of processed materials and reduce the waste of carving materials: When the bottom of the tool loses its processing ability, the tool is prone to breakage and collision with the processed material, resulting in the scrapping of the processed material.
[0042] 3) Protect machine tool components and extend machine tool life: Insufficient cutting ability of the tool can easily lead to tool damage and impact the CNC engraving machine, which may damage components such as electric spindle, guide rail, lead screw, and servo motor.
[0043] 4) Improve processing efficiency and save electricity: Improve processing efficiency, reduce processing time, and improve the utilization rate of electricity; reduce the idle running of the engraving machine after tool breakage and reduce the waste of electricity.
[0044] 5. It improved the productivity of machine tool operators and reduced their labor intensity. Attached Figure Description
[0045] Figure 1 This is a top view of the relief-carved part in the XY plane.
[0046] Figure 2 This is the XYZ isometric side view of the relief-carved part.
[0047] Figure 3 This is a structural diagram of a tapered ball end mill, a commonly used tool in CNC machining of stone relief.
[0048] Figure 4 This is a basic flowchart of the conventional path method for relief CNC machining.
[0049] Figure 5 This is a screenshot of the parameter settings interface for a ball end mill.
[0050] Figure 6 This is a screenshot of the parameter settings interface for a taper ball end mill.
[0051] Figure 7 This is a screenshot of the parameter settings interface for a tapered flat end mill.
[0052] Figure 8 This is a screenshot of the parameter setting interface for the processing strategy.
[0053] Figure 9 This is a screenshot of the interface for setting the processing path parameters.
[0054] Figure 10 This is a model illustration showing the cutting method.
[0055] Figure 11 This is a path diagram showing the parallel cutter path method.
[0056] Figure 12 This is a schematic diagram showing the processing path in a 3D relief model.
[0057] Figure 13 This is the XZ plane front view of the parallel section finishing path.
[0058] Figure 14This is a diagram showing the locations of the marked processing points.
[0059] Figure 15 This is a comparison result between the machining point and the comparison point, showing the tool movement diagram where point B is higher than point A.
[0060] Figure 16 This is a comparison result between the machining point and the comparison point. The tool movement diagram shows that point B and point A are at the same height.
[0061] Figure 17 This is a comparison result between the machining point and the comparison point, showing the tool movement diagram where point B is lower than point A.
[0062] Figure 18 This is a tool movement diagram showing the comparison results between the machining point and the comparison point, where point B is significantly lower than point A.
[0063] Figure 19 This is a schematic diagram showing the locations of the marked processing points under different processing paths.
[0064] Figure 20 It is a top view of the marked path segment in the XY plane.
[0065] Figure 21 This is a flowchart illustrating the specific process of processing the machining path or machining file for relief CNC machining according to the present invention.
[0066] Figure 22 This is a schematic diagram of the XZ plane angles for classifying the marked path segments into uphill segments, downhill segments, and horizontal segments.
[0067] Figure 23 This is a diagram showing the type of the "V-shaped" bottom of the marked path segment.
[0068] Figure 24 This is a comparison image of the "V"-shaped bottom of the marked path segment before and after it was flattened.
[0069] Figure 25 It is a toolpath diagram for horizontally layered, multi-stage machining of marked path segments.
[0070] Figure 26 It is a toolpath diagram for multiple machining operations by dividing the marked path segment into layers with equal Z-axis distances.
[0071] Figure 27 It is a toolpath diagram for combined layered multi-processing of marked path segments.
[0072] Figure 28 This is a schematic diagram showing the reverse cutting direction of the downhill path segment.
[0073] Figure 29 This is a schematic diagram of the structure marking the position of the reverse-moving tool on the downhill path segment.
[0074] Figure 30 This is a schematic diagram of the XZ plane angle of the medium-high path segment in step-type reciprocating side milling.
[0075] Figure 31 This is a schematic diagram of the XZ plane angle of the ascending path segment in step-type reciprocating side milling.
[0076] Figure 32 This is a schematic diagram of the XZ plane angle of the descending path segment in step-type reciprocating side milling.
[0077] Figure 33 This is a schematic diagram of the tool path structure when the single marked path segment is a downhill section.
[0078] Figure 34 This is a schematic diagram of the tool path structure when the composite marked path segment is a downhill section followed by a horizontal section. Figure 1 .
[0079] Figure 35 This is a schematic diagram of the tool path structure when the composite marked path segment is a downhill section followed by a horizontal section. Figure 2 .
[0080] Figure 36 This is a schematic diagram of the tool path structure when the composite marked path segment is a downhill section followed by a horizontal section. Figure 3 .
[0081] Figure 37 This is a schematic diagram of the toolpath structure for the "first path" of the parallel section finishing path. Figure 1 .
[0082] Figure 38 This is a schematic diagram of the toolpath structure for the "first path" of the parallel section finishing path. Figure 2 .
[0083] Figure 39 This is a schematic diagram of the toolpath structure for the "first path" of the parallel section finishing path. Figure 3 .
[0084] Figure 40 This is a schematic diagram of the XZ plane angles of the first path.
[0085] Figure 41 This is a schematic diagram of the XZ plane angles of the entire first path after multiple layered processing.
[0086] Figure 42 This is a schematic diagram of the XZ plane angles where the first path is divided into two segments.
[0087] Figure 43 This is the XY plane top view of the processing of the "path out of bounds" segment.
[0088] Figure 44It is a top view of the XY plane where the parallel section finishing path forms an angle with the horizontal line. Figure 1 .
[0089] Figure 45 It is a top view of the XY plane where the parallel section finishing path forms an angle with the horizontal line. Figure 2 .
[0090] Figure 46 It is a top view of the XY plane where the parallel section finishing path forms an angle with the horizontal line. Figure 3 . Detailed Implementation
[0091] The technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0092] like Figure 4 and Figure 21 As shown, a method for CNC machining of relief sculptures includes the following basic process: the CNC relief sculpture is first processed by programming software based on the three-dimensional model of the relief sculpture, by selecting tools and machining strategies, and inputting various machining parameters to calculate the machining path, which is then saved as a machining file. Finally, the machining is completed by a CNC engraving machine. This method is applicable to stone relief sculpture processing, wood relief sculpture processing, and steel relief sculpture processing.
[0093] The present invention can be configured to either calculate, analyze and modify the processing path after the step "calculate and generate processing path" to generate a new processing path, and then output the processing file; or it can be configured to calculate, analyze and modify the processing file after the step "output processing file" to obtain a new processing file.
[0094] Step 1: Generate a 3D relief model: There are three main ways to generate a 3D relief model using CAM programming software: (1) Input a 3D model file, such as STL; (2) Input a grayscale image and generate a 3D relief model based on the grayscale image; (3) Open a file containing a 3D model.
[0095] Step 2: Modify the 3D relief model: (1) Edit and modify the shape of the 3D relief model; (2) Modify the model size, including width (X-axis horizontal dimension), length (Y-axis vertical dimension), and depth (Z-axis vertical dimension).
[0096] Step 3: Select the cutting tool and machining strategy, and input the parameters.
[0097] (1) Tool type and tool geometry parameters: Commonly used finishing tools for CNC relief carving include ball end mills, tapered ball end mills, and tapered flat end mills. For example... Figure 5 The radius R of the ball-end cutter shown is half the diameter D. For example... Figure 6 The bottom of the tapered ball end mill shown is a semicircle, the radius of which is called the fillet radius R. Figure 7 The tapered flat-bottomed knife shown.
[0098] (2) Processing strategy: Taking a certain programming software as an example, such as Figure 8 As shown, the processing strategies include: hole processing, curve processing, area processing, surface processing, projection processing, and image processing. Relief carving is a type of surface processing, and relief carving processing belongs to surface processing.
[0099] like Figure 8 As shown, surface machining strategies include: layered area roughing, projection deepening roughing, and surface finishing. To improve machining efficiency, when not using a roughing strategy for relief machining, the user selects the surface finishing strategy and creates the machining path, such as... Figure 9 As shown.
[0100] (3) Input the various processing parameters.
[0101] Machining parameter 1: Select the tool feed mode. For example... Figure 10 As shown, the tool path methods for surface finishing include parallel section, contour, radial radial, surface streamline, equidistant surrounding, and angular partitioning. In CNC relief finishing, the most commonly used tool path method for surface finishing is the parallel section.
[0102] Machining parameter 2: Parallel cut-out path mode. Path angle refers to the angle between the tool's engraving direction and the horizontal line of the X-axis. For example... Figure 11 As shown, this includes path angles of 0 degrees, 45 degrees, and 90 degrees; reciprocating tool movement (bidirectional tool movement); and non-reciprocating tool movement (unidirectional tool movement).
[0103] Machining Parameter 3: Steep Slope. In parallel section finishing paths, to avoid steep paths, the steep slope machining parameter can be used to limit the machining range. The angle with the horizontal plane represents the angle between the path and the horizontal plane. When machining flat surfaces, the angle between the machining path and the horizontal plane must not exceed this angle; any steep portions exceeding this angle are truncated and removed. All Faces: Machining all faces without filtering steep paths; Flat Surface Mode: Machining relatively flat curved surfaces and deleting relatively steep paths; Add Vertical Parallel Path: Based on the surface orientation, the path in a local area follows the vertical direction of the original path.
[0104] Processing parameter 4: Depth range, the depth of surface processing.
[0105] Surface height refers to the height of the upper surface of the machining area from the zero plane of the Z-axis. When the surface height is 0, the upper surface of the machining area is on the zero plane of the Z-axis.
[0106] Bottom surface height refers to the height of the lower surface of the machining area from the zero plane of the Z-axis. The bottom surface height cannot be greater than the surface height.
[0107] Machining depth: The Z-axis height of the upper surface of the machining area from the lower plane. Machining depth = surface height - bottom surface height.
[0108] Processing Parameter 5: Path Spacing. In CNC relief carving, the path spacing is typically between 0 and 1 millimeter. Higher precision requirements necessitate a smaller path spacing and longer processing time; lower precision requirements require a larger path spacing and shorter processing time. The harder the carving material, the smaller the path spacing; the softer the material, the larger the path spacing.
[0109] Based on the design requirements of the carving material and the 3D relief model, set the machining allowance, path spacing, tool feed method, geometry, tool speed, operation settings, machining accuracy, machining sequence, sharp corner settings, and contour settings.
[0110] Step 4: Calculate and generate the processing path.
[0111] The machining path, also known as the cutting path or machining route, consists of a series of tool positions, which determine the tool's movement trajectory and the settings of cutting parameters. In the process of carving reliefs on a three-axis CNC engraving machine, the tool position refers to the coordinate position of the center point of the tool's bottom, such as... Figure 12 As shown.
[0112] Taking the parallel cross-section finishing path for carving stone as an example, the processing path is calculated and generated as follows:
[0113] 1) Disadvantages of parallel section finishing paths.
[0114] There are many finishing paths, the most common of which are "parallel section finishing", "equidistant shape finishing", "radial radial finishing", "curved surface streamline finishing", "circular equidistant finishing", and "angle partition finishing".
[0115] The finishing path for CNC stone relief carving mainly uses the "parallel section finishing path". The parallel section finishing path is widely used in CNC stone relief carving. It is suitable for situations where the curved surface is relatively complex, but there are not many steep surfaces. On steep curved surfaces, the cutting depth at the bottom of the tool is large, which can easily cause tool damage.
[0116] like Figure 13 As shown, the main drawback of using the "parallel section finishing path" for CNC stone relief carving is that the cutting amount at the bottom of the tool is not uniform throughout the entire processing. When the cutting amount is too large, the bottom of the tool wears too much. When the bottom of the tool is damaged, the tool loses its processing ability and is scrapped.
[0117] Nowadays, CNC engraving machines are becoming increasingly sophisticated in their configuration and faster in their feed speed. However, the uneven processing volume of "parallel cutting line finishing path" makes the cutting tools prone to damage, which seriously affects the high-speed processing effect of CNC stone relief carving and severely restricts the development of the CNC stone relief carving industry.
[0118] 2) This invention uses a path calculation method for marking machining points to calculate the depth of the tool bottom center point into the material, classify the machining points in the "parallel section finishing path", and decide whether to "mark" them according to the type.
[0119] The parallel section finishing path is processed line by line in sequence. The distance between each two adjacent lines is very small. The processing depth of the current line is directly related to the processing depth of the previous line that has been processed.
[0120] like Figure 14 As shown, there is a processing point B in the current row. In the top view (XY view) of the path, draw a perpendicular line from point B to the path of the next row. The foot of the perpendicular is point A. That is, point A is the processing point of the previous row that is closest to point B in the top view. The planar distance between point A and point B in the top view is a "path spacing". At this time, point A is called the "comparison point" of point B.
[0121] Definitions of "comparison point" and "Z-axis comparison distance": In the top view (XY view) of the relief path, there is a processing point B in the current row path and a processing point A in the previous row path. The planar distance between point A and point B is a "path spacing". At this time, point A is called the "comparison point" of point B, and the Z-axis distance between point A and point B is called the "Z-axis comparison distance".
[0122] "Z-axis comparison distance" is the depth to which the center point of the tool bottom cuts into the material at the current machining point.
[0123] Point B is the processing point on the current path, and point A is the processing point on the previous path. Figure X In the Y-plane view, point A is the perpendicular foot (closest point) of point B on the upper path. At this time, point A is called the comparison point of point B.
[0124] In this invention, all distance and length units are millimeters (mm).
[0125] like Figure 14As shown, the vertical distance from machining point A to the Z-axis zero plane (material surface) in the path is OA, and the Z-axis coordinate is -OA; the vertical distance from machining point B to the Z-axis zero plane is OB, and the Z-axis coordinate is -OB. When the machining path reaches machining point B, the depth to which the bottom of the tool cuts into the material is AB = OB - OA, which is the Z-axis coordinate of point A minus the Z-axis coordinate of point B. For example, if the Z-axis coordinate of point A is -10 and the Z-axis coordinate of point B is -10.5, then AB = 0.5 mm.
[0126] The shapes of relief sculptures are complex and diverse. The machining depth of the "parallel section path" in the Z-axis direction is constantly changing, and the depth of the tool's entry into the material is also constantly changing. This change is not uniform, but varies with the steepness of the surface. The smaller the depth of the tool's entry into the material, the less wear on the tool bottom; the greater the depth of the tool's entry into the material, the greater the wear on the tool bottom.
[0127] In this invention, the user sets a value called "Z-axis contrast distance mark value". This value will vary when processing different materials and using different tools. For example, in CNC stone relief processing, the "Z-axis contrast distance" is usually set between 0.15 and 0.5 mm.
[0128] Let the “Z-axis comparison distance mark value” be d, the depth of the tool bottom cutting into the material be h, and the path spacing be p.
[0129] A deep comparison between the processing point and the comparison point yields the following three results:
[0130] (1) When h≤0, the bottom of the tool does not cut into the material, which is called the "non-cutting point" and is not marked. Figures 15-16 As shown;
[0131] (2) When 0 < h ≤ d, the bottom of the tool cuts into the material, but the machining depth is small. This is called a "slight entry machining point" and is not marked. Figure 17 As shown;
[0132] (3) When h > d, the tool bottom cuts into the material to a large depth, which is called a "severe cutting point". This type of point is marked and called a "marked point". Unmarked points are called "unmarked points". Figure 18 As shown.
[0133] This invention aims to solve the problem of easy wear on the bottom of the tool during relief CNC machining. It first identifies the machining points prone to wear in the finishing path. By comparing the depth of the machining point and the comparison point, the difference in depth is obtained. This difference is then compared with a user-inputted value (Z-axis comparison distance marker value) to mark the machining point.
[0134] like Figure 19 As shown, in the "parallel section finishing path", the angle between the path and the horizontal line is called the "path angle". Common path angles are 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees. When the path angle is not 0 degrees, the algorithm for "marking the processing point" still holds true.
[0135] This method of obtaining marked machining points is not limited to "parallel section finishing path", but is also applicable to "circumferential equidistant finishing" and "spiral equidistant finishing".
[0136] The machining direction of the "circular equidistant finishing" path has two types: "from inside to outside" and "from outside to inside". Figure 19 In the "circumferential equidistant finishing" shown, the machining direction is "from inside to outside". In the XY top view, draw a perpendicular line from point B upwards along a path, with the foot of the perpendicular at point A. The planar distance between points B and A in the top view is one "path spacing". Therefore, point A is the comparison point for point B. For the two machining directions, "from inside to outside" and "from outside to inside", the machining order of the points is reversed, as shown below. Figure 19 In the “circumferential equidistant finishing” shown, when the machining direction changes from “from inside to outside” to “from outside to inside”, the machining point and the comparison point are interchanged. At this time, point B is the comparison point of point A.
[0137] The machining direction of the "spiral equidistant finishing" path has two options: "from inside to outside" and "from outside to inside". Figure 19 In the "spiral equidistant finishing" shown, the planar distance between point B in the current path and point A in the previous path in the XY top view is one "path spacing," so point A is the comparison point for point B. For the two machining directions, "from inside to outside" and "from outside to inside," the machining order of points is reversed, as shown... Figure 19 In the “spiral equidistant finishing” shown, when the machining direction changes from “from inside to outside” to “from outside to inside”, the machining point and the comparison point are interchanged. At this time, point B is the comparison point of point A.
[0138] The significance of finding a comparison point lies in calculating the "Z-axis comparison distance," which is the depth of the tool's bottom center point into the material. This depth is then compared with the user-input value to determine whether the point should be marked. Even if the planar distance between the comparison point and the machining point in the top view is not equal to a "path spacing" but is an approximation, it is still within the protection scope of this algorithm. Finishing types are not limited to the "parallel section finishing path," "circling equidistant finishing path," and "spiral equidistant finishing path" listed above. In other types of finishing paths, finding a comparison point for the current machining point in the previous path is also within the protection scope of this algorithm.
[0139] 3) Marking the composition of the path segment. The machining path of CNC relief carving is composed of numerous machining points connected by line segments to fit the curved surface, achieving an effect close to curved surface machining. The machining path is composed of path segments, which are composed of machining points and have a machining direction. Two adjacent machining points form a "path sub-segment".
[0140] like Figure 20 As shown, a set of processing points are arranged in sequence. The line segments formed by connecting two adjacent processing points are called "path segments", such as line segments 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, etc.
[0141] A path segment consisting of two adjacent marked points is called a "marked path segment", and a path segment that does not belong to a "marked path segment" is called an "unmarked path segment".
[0142] A path segment consisting of adjacent "marked path segments" is called a "marked path segment", and a path segment that does not belong to a "marked path segment" is called an "unmarked path segment".
[0143] A "marked path segment" consists entirely of marked points and cannot contain any unmarked processing points. For example... Figure 20 As shown, assuming 1, 2, 3, 5, 6, 7, 10, 11, and 12 are marked points and the rest are unmarked points, then the path segments 1-2-3, 5-6-7, and 10-11-12 are marked path segments, and the path segments 3-4-5, 7-8-9-10, and 12-13-14 are unmarked path segments.
[0144] 4) such as Figure 22 As shown, based on the angle between the "marked path segment" and the horizontal line, it is classified into: "marked horizontal path segment", "marked uphill path segment", and "marked downhill path segment". The angle value is input by the user and is called the "uphill / downhill angle". The angle between the "marked path segment" and the horizontal line is calculated. Path segments with an angle smaller than the "uphill / downhill angle" are called "marked horizontal segments"; path segments with an angle greater than or equal to the "uphill / downhill angle" and processed upwards are called "marked uphill segments"; and path segments with an angle greater than or equal to the "uphill / downhill angle" and processed downwards are called "marked downhill segments".
[0145] A path segment consisting of "marked horizontal sub-segments" is called a "marked horizontal path segment"; a path segment consisting of "marked uphill sub-segments" is called a "marked uphill path segment"; and a path segment consisting of "marked downhill sub-segments" is called a "marked downhill path segment".
[0146] 5) Flatten the bottom of the marked path segment in a "V" shape. Among the marked path segments, there is a type of path segment that resembles a "V" shape, called a "marked V-shaped segment".
[0147] like Figure 23 As shown, there are two types:
[0148] Type 1: Path segment AB is marked as "downhill"; path segment BC is marked as "uphill".
[0149] Type 2: Path segment AB is marked as "downhill section"; path segment CD is marked as "uphill section"; the middle path segment BC is marked as "horizontal section", but its width is smaller than the user-input value "V-shaped recognition width".
[0150] The bottom horizontal width of the "marked V-segment" is very small and narrow. When the tool is machining this part, the downward cutting amount of the tool is large, the coolant is difficult to enter, and the material residue is not easy to be discharged, resulting in very large wear at the bottom of the tool.
[0151] Relief carving is mainly used to showcase the aesthetic appeal of an appearance. Its processing precision requirements are not high. The bottom of the "marked V-shaped segment" can be flattened to a certain extent along the horizontal line to remove the narrow "sharp corners" at the bottom, which has a significant effect on reducing the wear of the tool bottom.
[0152] The "flattening width" value input by the user serves as a reference parameter to control the "bottom horizontal width" after flattening, such as... Figure 24 As shown.
[0153] 6) The method of changing the toolpath by "marking path segments".
[0154] (I) Z-axis layered multi-stage machining. This significantly reduces tool wear. Although the toolpath length appears to increase, the feed rate can be set very high, keeping the machine in a high-speed machining state. Therefore, layered multi-stage machining, especially on harder materials such as granite, reduces tool wear and improves machining efficiency. Different layering methods are used in different situations for Z-axis layered multi-stage machining. Here are three different methods:
[0155] (1) Layered processing in the horizontal direction. Divide the Z-axis distance between the highest point of the previous path segment and the lowest point of the current path segment into equal parts, and perform layered processing multiple times along the horizontal direction, such as... Figure 25 As shown.
[0156] (2) "Equal Z-axis distance division" layered multiple processing. Divide the vertical Z-axis distance between the two paths into equal parts, and then connect the division points sequentially, such as... Figure 26 As shown.
[0157] (3) "Combined" layered multi-stage processing. First, use "horizontal layering," then use "Z-axis distance equal division layering," combining the two methods for layered multi-stage processing, such as... Figure 27 As shown.
[0158] (ii) Reverse toolpath for the "marked downhill path segment". Reversing the toolpath for the "marked downhill path segment" changes the cutting position at the bottom of the tool, reducing tool wear. Figure 28 As shown. The original path segment was from point A to point B. The direction is reversed, becoming from point B to point A.
[0159] like Figure 29 As shown, the cutting direction is different for uphill and downhill path segments, and the position of the material being cut by the bottom of the tool is also different.
[0160] Figure 29 Point Q on the left is the tangent point (contact point) between the bottom arc of the tool and the inclined line AB. Points M and N are the intersection points of the tool profile and the workpiece surface. In the downhill path segment, the tool cuts downwards, and the position where the tool cuts material is the part between Q and N, which includes the center of the tool bottom. The center point of the tool bottom participates in the cutting.
[0161] Figure 29 Point Q on the right side is the tangent point (contact point) between the bottom arc of the tool and the inclined line AB. Points M and N are the intersection points of the tool profile and the workpiece surface. In the uphill path segment, the tool cuts upwards, and the position of the tool cutting material is the part between MQ, excluding the center of the tool bottom. The center point of the tool bottom does not participate in the cutting. The larger the angle between the marked path segment and the horizontal line, the farther away the tool's cutting position is from the center point of the tool bottom.
[0162] Reverse the cutting path of the marked downhill section to change the cutting position at the bottom of the tool and reduce tool wear.
[0163] (III) Step-by-step reciprocating side milling. In the process of relief CNC machining, some path sections have large cutting volumes, which can easily cause tool breakage and rapid wear. Step-by-step reciprocating side milling uses a one-forward-one-backward method, which indirectly reduces the machining speed and facilitates tool cooling and removal of machining residue during tool retraction.
[0164] In step-by-step reciprocating side milling, there are three parameters: side milling step distance: the horizontal distance the tool travels along the path to cut the material in a single advance; retraction length: the defined retraction length of the tool along the path each time it retracts; and Z-axis depth of cut: the maximum cutting depth of the tool in the Z-axis direction each time it advances in the descending path segment.
[0165] Because the shape of the relief path varies greatly, the step-by-step reciprocating side milling process is divided into three cases and corresponding algorithms are used.
[0166] (1) Equal-height path segment: All machining points on the path segment have the same Z-axis height, such as Figure 30 As shown, the path segment AH undergoes step-by-step reciprocating side milling, with the following steps:
[0167] ① First, advance one "side milling step" from starting point A along the path, and then reach point B.
[0168] ② Retreat from point B. If the path length between A and C is greater than the "retreat length", retreat by one "retreat length"; if the horizontal distance between A and B is less than or equal to the "retreat length", retreat only to point A. That is, you cannot cross the starting point when retreating.
[0169] ③ Continue advancing along the path by one "side milling step" to point C, and then retreat from point C. If the distance between A and C is greater than the "retreat distance", retreat by one "retreat length"; if the distance between A and C is less than or equal to the "retreat length", retreat to point A.
[0170] ④ Continue in this manner... until point H is reached, at which point no further retreat is taken.
[0171] (2) Ascending path segment: The Z-axis height of the next machining point is always higher than that of the previous machining point. For example... Figure 31 As shown, the path segment AH undergoes step-by-step reciprocating side milling, with the following steps:
[0172] ① Start from point A and proceed along the path. The horizontal distance you advance is one "side milling step" until you reach point B.
[0173] ② Move backward from point B along the path. If the path length between A and B is greater than the "backward length", then move backward by one "backward length"; if the path length between A and B is less than or equal to the "backward length", then only move backward to point A. That is, the backward movement cannot cross the starting point.
[0174] ③ Continue along the path to point C. The horizontal distance between point C and point B is one "side milling step". Then retreat from point C. If the path length between A and C is greater than the "retreat length", retreat by one "retreat length"; if the path length between A and C is less than or equal to the "retreat length", retreat to point A.
[0175] ④ Continue in this manner... until point H is reached, then stop moving backward.
[0176] (3) Descent path segment: The Z-axis height of the next machining point is always lower than that of the previous machining point. For example... Figure 32 As shown, the path segment AH undergoes step-by-step reciprocating side milling, with the following steps:
[0177] ① Start from point A and move along the path. There are two constraints on moving forward: the horizontal movement distance cannot exceed the "side milling step distance", and the vertical movement distance cannot exceed the "Z-axis depth of cut". Moving forward from point A, although the horizontal movement distance at point B does not exceed the "side milling step distance", the vertical movement distance has reached the "Z-axis depth of cut", so the movement can only go to point B.
[0178] ② Move backward from point B along the path. If the path length between A and B is greater than the "backward length", then move backward along the path by one "backward length"; if the path length between A and B is less than or equal to the "backward distance", then only move backward to point A. That is, the backward movement cannot cross the starting point.
[0179] ③ Continue along the path to point C. The horizontal distance between point C and point B cannot exceed the "side milling step distance," and the vertical distance cannot exceed the "Z-axis depth of cut." Then retreat from point C. If the path length between A and C is greater than the "retreat length," retreat along the path by one "retreat length." If the path length between A and C is less than or equal to the "retreat length," retreat only to point A. That is, the retreat cannot cross the starting point.
[0180] ④ Continue in this manner... until point H is reached, then stop moving backward.
[0181] 7) "Marked Path Segment" changes the toolpath strategy. "Marked Path Segment" is divided into "Single Marked Path Segment" and "Compound Marked Path Segment".
[0182] If a “marked path segment” contains only one of the following: “marked horizontal path segment”, “marked uphill path segment”, or “marked downhill path segment”, then the “marked path segment” is called a “single marked path segment”.
[0183] If a “marked path segment” contains two or more of the following: “marked horizontal path segment”, “marked uphill path segment”, and “marked downhill path segment”, then the “marked path segment” is called a “composite marked path segment”.
[0184] (a) When a “single marked path segment” is a “horizontal segment”, use “Z-axis distance equal division” to process it in layers multiple times.
[0185] (ii) When the “single marked path segment” is an “uphill segment”, the tool path is not changed and the tool moves along the original path. When moving the tool in a “marked uphill path segment”, the tool path is not changed because the cutting position of the tool is far from the center point of the bottom of the tool.
[0186] (iii) When a "single marked path segment" is a "downhill segment," reverse the cutting direction to change it from "downhill" to "uphill." For example... Figure 33As shown, segment AB in the current path segment is a "marked path segment", while other path segments are not "marked path segments", so AB is a "single marked path segment".
[0187] The "single marked path segment" AB is a "downhill segment." The modified path is as follows: Starting from point A, ascend along the positive Z-axis to point C, then move laterally along the horizontal line to point E (point E is directly above point B on the Z-axis). Descend along the negative Z-axis to point B, and process the path segment in reverse from point B to point A. From point A, ascend along the positive Z-axis to point C, then move laterally along the horizontal line to point E, and finally descend to point B. This path segment is now complete, and processing of subsequent paths continues.
[0188] (iv) When a “composite marked path segment” is a “downhill segment” followed by a “horizontal segment”.
[0189] (1) When the angle between the previous path segment corresponding to the horizontal segment of the currently marked path segment and the horizontal line is less than the "angle of the uphill / downhill segment", the segment is processed in a "combined" layered manner multiple times. For example, the slope of segment FG in the figure below is relatively small.
[0190] like Figure 34 As shown, segments MA and CD of the current path segment are not marked path segments, while segment ABC is a marked path segment. Among them, path segment AB is a "marked downhill path segment", and path segment BC is a "marked horizontal path segment".
[0191] The modified path for segment ABC is as follows: Starting from point A, ascend along the positive Z-axis to point E, then move laterally along the horizontal line to point J (point J is directly above point B on the Z-axis). Descend along the negative Z-axis to point F. From point F, perform "combined layered multiple processing" on the area enclosed by points FGCB, ending at point B. From point B, process segment AB in reverse, ending at point A. From point A, ascend along the positive Z-axis to point E, then move laterally along the horizontal line to point K, and finally descend to point C. At this point, the processing of segment ABC is complete.
[0192] (2) If the previous path segment corresponding to the horizontal segment of the current marked path segment has a segment with an angle greater than or equal to the "angle of the uphill and downhill segments", first perform step-by-step reciprocating side milling on that segment, then perform combined layered multi-processing on the remaining area, and finally perform reverse processing on the "downhill segment". As shown in the figure below, the ND segment has a large slope.
[0193] like Figure 35As shown, GH and MD are horizontal lines, and HB, DF, and EC are vertical lines. The current path segment ABFC is a "marked path segment". Because it is a "marked path segment", the Z-axis height of all processing points on this path segment from the previous path segment exceeds the user-input value, such as the height of line segments AG, BN, FD, and CE.
[0194] If using "Z-axis layered multi-stage machining" and "reverse tool movement on downhill path segments," the strategy is as follows: Starting at point A, first raise the tool along the positive Z-axis to point G, then move it horizontally to point H. Descend along the negative Z-axis to point N. Perform "Z-axis multi-stage layered machining" on the area enclosed by points N, D, E, C, F, with point B as the final point of the multi-stage machining. Starting from point B, reverse-machine the AB path segment to point A. Raise the tool at point A to point G, then move it horizontally to point J, and then descend to point C, completing the machining. Performing Z-axis multi-stage layered machining on the area enclosed by points N, D, E, C, F, and F, due to the steepness between curve segments ND, results in a larger Z-axis height (NB) in this area.
[0195] Starting from point D, perform "stepping reciprocating side milling" along the horizontal line to the left in the area enclosed by point NDM. After this area is cleared, the area that needs to be machined in multiple layers along the Z-axis, which was originally enclosed by point NDECFB, becomes the area enclosed by point MDECFB. The total height of the Z-axis is reduced, which can improve machining efficiency and reduce tool wear.
[0196] like Figure 36 As shown, starting from point D, the DM segment is subjected to "step-by-step reciprocating side milling". The steps are as follows:
[0197] ①Starting from point D, move forward one "side milling step" distance to the left to reach point S, and then move backward one "backward length" to the right. If the distance between line segments SD is less than the "backward length", then you can only retreat back to point D, that is, you cannot cross the starting point D when retreating.
[0198] ② Continue moving left from point D to point T. The horizontal distance between point T and point S is one "side milling step". Then retract the tool to the right to point D (because the distance from point T to point D is less than the "retraction length", it cannot cross the starting point D and can only reach the starting point D).
[0199] ③ Continue moving left from point D to point U. The horizontal distance between point U and point T is one "side milling step". Then retract the tool to the right to point D (because the horizontal distance from point U to point D is less than the "retraction length", it cannot cross the starting point D and can only reach the starting point D).
[0200] ④ Continue moving left from point D to point V. The horizontal distance between point V and point U is one "side milling step". Then retract the tool to the right to point R (the horizontal distance from point V to point R is the "retraction length").
[0201] ⑤ Continue moving left from point R to point M (because point M is the end point of "stepping reciprocating side milling", the tool will not retract to the right here). At this time, the "stepping reciprocating side milling" of segment DM is completed.
[0202] (v) When a composite marked path segment is a horizontal segment followed by a downhill segment, and then another horizontal segment. When a composite marked path segment is a horizontal segment followed by a downhill segment, and then another horizontal segment, the first horizontal segment is first processed in layers using equal Z-axis distance, and then the second horizontal segment is processed in layers. If the previous path segment corresponding to the current path segment locally meets the characteristics of step-by-step reciprocating side milling, then step-by-step reciprocating side milling is performed before layer processing. Layer processing uses combined layer processing multiple times, and then the downhill segment is processed in reverse.
[0203] 8) Machining of the "first line path" of the parallel section finishing path. The "first line path" of the parallel section finishing path is a special line path. Depending on the position of the first line path in the material, there are three cases:
[0204] (1) In the first path, the tool processes the material from the outside, but there is actually no cutting. Figure 37 As shown.
[0205] (2) In the first path, the tool is machining inside the material, which is a "heavy load cutting" situation, such as... Figure 38 As shown.
[0206] (3) In the first path, the tool partially processes the outside of the material and partially processes the inside of the material. When the tool spends more time inside the material, it is also a case of "heavy-load cutting," such as... Figure 39 As shown.
[0207] like Figures 40-41 As shown, when the first path has a "heavy load cutting" situation, there are two common processing methods for it, and both of these situations have certain drawbacks.
[0208] ① By adjusting the "feed ratio," the feed rate is set to a very slow speed before machining. For example, adjusting the "feed ratio" to 1% to 5% results in an actual feed rate of approximately 30 to 300 mm / min. Although this machining method does not take long, during the machining process, especially when the tool is machining vertically or diagonally downwards, coolant has difficulty entering and machining residue has difficulty being removed. The bottom of the tool continues to heat up, leading to a certain degree of wear on the tool bottom.
[0209] ② The first line of the path is processed in multiple layers. This method of processing the entire path in multiple layers is very time-consuming and inefficient.
[0210] Example of time usage: If the depth of the lowest point of the first path is 30 mm, and the Z-axis depth of cut for layered machining is 0.2 mm, then there are 150 layers. If the average machining time for each layer is 20 seconds, then the total time is 3000 seconds.
[0211] like Figure 42 As shown, the first path AC is broken at point B, dividing it into segments AB and BC. The horizontal width of segment AB is called the "groove width," which is input by the user. Therefore, the actual position of point B can be set by the user through inputting a value.
[0212] The AB segment of the first path is called the "grooving section," which is processed in layers and multiple times; the BC segment is called the "stepping reciprocating side milling section," which is processed by "stepping reciprocating side milling."
[0213] ① Grooving: Use a "combined" layered, multiple-stage processing method. First, use "horizontal layering," then use "equal Z-axis distance layering," combining the two methods for layered, multiple-stage processing.
[0214] ② Stepping reciprocating side milling: Use "stepping reciprocating side milling".
[0215] 9) Processing "Path Exceedance Segment": When the length of the current path exceeds that of the previous path, the excess path segment is called a "path excess segment." For example... Figure 43 As shown, path segment BC is the part that extends beyond the previous path and is called the "path-exceeding segment". The "path-exceeding segment" is machined using "stepping reciprocating side milling".
[0216] 10) When the parallel section finishing path has an angle with the horizontal line.
[0217] like Figure 44 As shown, when the parallel section finishing path has an angle α with the horizontal line, first rotate the entire path around any point W by an angle of α to transform it into a path with an angle of 0 with the horizontal line, process it, and then rotate it back to a path with an angle of α with the horizontal line using that point as the center. Finally, output the machining file.
[0218] like Figures 45-46 As shown, the entire path is rotated to become a path with an angle of 0 degrees to the horizontal line. This process is then performed. The resulting new path is then rotated in the opposite direction to become a path with an angle of α to the horizontal line. Finally, the processed file is output.
[0219] Step 5: Output the machining file, usually a G-code file, with NC being a common format.
[0220] Step 6: CNC engraving machine processing. Load the processing file into the control system of the CNC engraving machine for processing.
[0221] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.
[0222] The technologies, shapes, and structures not described in detail in this invention are all known technologies.
Claims
1. A path method for CNC machining of relief carving, characterized in that, Includes the following steps: S1. Generate a 3D relief model: CAM programming software generates a 3D relief model; S2. Modify the 3D relief model: Edit and modify the shape of the 3D relief model; S3. Select the tool and machining strategy, and input various machining parameters, including but not limited to tool type, machining strategy, and machining path parameters; S4. Calculate and generate machining path: Using an algorithm to mark machining points, find machining points that are prone to wear in the finishing path. By comparing the depth of the machining points and the comparison points, the depth difference between the machining points and the comparison points is obtained. The depth difference is compared with the value input by the user to obtain the marked machining points. The machining path of the tool is determined by marking the machining points. The machining path is automatically calculated, analyzed and modified to generate a new machining path. S5. Output processing file: Generate a processing file from the new processing path in step S4; or the user can skip steps S1-S3 and directly input an existing relief processing file to generate a processing path, and then perform the operation in step S4 to recalculate, analyze and modify the processing path to obtain a new processing file. S6. CNC engraving machine processing: The final processing file is loaded into the control system of the CNC engraving machine for processing.
2. The path method for relief CNC machining according to claim 1, characterized in that, In step S1, the CAM programming software generates a three-dimensional relief model. The three-dimensional relief model file includes, but is not limited to, inputting a three-dimensional model in STL format, inputting a grayscale image into the CAM programming software and generating a three-dimensional relief model based on the grayscale image, and opening a file containing a three-dimensional model.
3. The path method for relief CNC machining according to claim 1, characterized in that, The size modification of the three-dimensional relief model in step S2 includes width (X-axis horizontal dimension), length (Y-axis vertical dimension), and depth (Z-axis vertical dimension).
4. The path method for relief CNC machining according to claim 1, characterized in that, The types of cutting tools used in step S3 include, but are not limited to, ball end mills, tapered ball end mills, and tapered flat end mills; The machining strategy adopts a surface machining strategy, which is a surface finishing strategy; The machining path parameter settings include the tool path mode, which includes, but is not limited to, parallel section finishing, circumferential equidistant finishing, and spiral equidistant finishing.
5. The path method for relief CNC machining according to claim 1, characterized in that, The algorithm for marking machining points in step S4 is to calculate the depth of the tool's bottom center point into the material. In all tool path types, the distance between each two adjacent paths is very small. The machining depth of the current path is directly related to the machining depth of the previous path that has been completed. There is a machining point B in the current path. In the XY view of the path, a perpendicular line is drawn from point B to the previous path, with the foot of the perpendicular being point A. Point A is located on the previous path, that is, point A is the machining point of the previous path that is closest to point B in the XY view. The planar distance between point A and point B in the XY view is a "path spacing". At this time, point A is called the "comparison point" of point B, and the Z-axis distance between point A and point B is called the "Z-axis comparison distance". "Z-axis comparison distance" is the depth to which the center point of the tool bottom at the current machining point cuts into the material in the Z-axis direction; The "Z-axis comparison distance marker value" is set to d (user input parameter), and the "Z-axis comparison distance" is set to h. A depth comparison is performed between the machining point and the comparison point, resulting in the following three outcomes: (1) When h≤0, the center point of the bottom of the tool does not cut into the material, which is called the "non-cutting point" and is not marked. (2) When 0 < h ≤ d, the center point of the tool bottom cuts into the material, but the machining depth is small. This is called the "slight cutting point" and is not marked. (3) When h > d, the center point of the bottom of the tool cuts into the material and the machining depth is large. This is called a "severe cutting point". Mark it. This type of machining point is called a "marked point". The unmarked point is called an "unmarked point".
6. The path method for relief CNC machining according to claim 5, characterized in that, The marked processing points form marked path segments. The relief processing path is composed of numerous processing points connected by line segments to fit the curved surface. A local path composed of several adjacent processing points is called a "path segment". The relief processing path is composed of path segments, and path segments are composed of processing points. A small path segment composed of two adjacent processing points is called a "path sub-segment". All processing points on the relief processing path are divided into two types: "unmarked points" and "marked points". "Unmarked points" form "unmarked path segments", and "marked points" form "marked path segments". Two adjacent "marked points" form a "marked path sub-segment", and several adjacent "marked path sub-segments" form a "marked path segment". That is, all processing points in a "marked path segment" are "marked points". The marked path segment is composed of "marked points" and has a processing direction. If the processing points adjacent to both sides of a "marked point" are "unmarked points", then this point is called a "marked isolated point" and is not processed.
7. The path method for relief CNC machining according to claim 6, characterized in that, The angle between the marked path segment and the horizontal line is compared with the angle value input by the user and classified into marked horizontal path segments, marked uphill path segments, and marked downhill path segments. The angle value input by the user is called the uphill / downhill angle. The angle between the marked path segment and the horizontal line is calculated. Path segments with angles smaller than the uphill / downhill angles are called marked horizontal path segments; path segments with angles greater than or equal to the uphill / downhill angles and with the processing direction upward are called marked uphill path segments; path segments with angles greater than or equal to the uphill / downhill angles and with the processing direction downward are called marked downhill path segments; path segments composed of marked horizontal path segments are called marked horizontal path segments; path segments composed of marked uphill path segments are called marked uphill path segments; and path segments composed of marked downhill path segments are called marked downhill path segments.
8. The path method for relief CNC machining according to claim 7, characterized in that, The bottom of the marked path segment is flattened in a "V" shape. The user inputs a value for "flattening width" as a reference parameter to control the "bottom horizontal width" after flattening.
9. The path method for relief CNC machining according to claim 7, characterized in that, The method of changing the tool path of the marked path segment includes Z-axis layered multiple machining, marked downhill path segment reverse tool path, and step-type reciprocating side milling. The Z-axis layered multiple machining steps include: (1) horizontal layered multiple machining, (2) Z-axis distance equally divided layered multiple machining, and (3) combined layered multiple machining. Mark the downhill path segment and reverse the tool path to change the original machining direction from high point to low point to low point to high point. Reverse the direction and change the cutting position of the bottom of the tool. Step-type reciprocating side milling adopts a one-forward-one-backward method, which indirectly reduces the processing speed and facilitates tool cooling and removal of processing residue when retracting the tool. Step-type reciprocating side milling is divided into three cases and uses corresponding algorithms: (1) Equal height path segment: all processing points on the path segment have the same Z-axis height, (2) Ascending path segment: the Z-axis height of the next processing point is always higher than the previous processing point, (3) Descending path segment: the Z-axis height of the next processing point is always lower than the previous processing point.
10. The path method for relief CNC machining according to claim 7, characterized in that, The strategy for changing the tool path by marking the path segment is as follows: the marking path segment is divided into a single marking path segment and a compound marking path segment; if the marking path segment contains only one of the following: a horizontal marking path segment, an uphill marking path segment, or a downhill marking path segment, then the marking path segment is called a single marking path segment; if the marking path segment contains two or more of the following: a horizontal marking path segment, an uphill marking path segment, or a downhill marking path segment, then the marking path segment is called a compound marking path segment. The machining of the path segment that exceeds the segment is performed using step-by-step reciprocating side milling.